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For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall. In most cases, the mean velocity is used. [18] There are many ways to measure blood flow velocity, like videocapillary microscoping with frame-to-frame analysis, or laser Doppler anemometry. [19]
At this stage the majority of the flow can be described with velocity vectors normal to the entrance, but in plane velocities tangent to the flow are present. [3] As the path starts to curve in the ascending aorta, the blood towards the outside of the arch tends to rotate towards the inner wall, causing a helical pattern that is observed in ...
Vascular resistance occurs when the vessels away from the heart oppose the flow of blood. Resistance is an accumulation of three different factors: blood viscosity, blood vessel length and vessel radius. [30] Blood viscosity is the thickness of the blood and its resistance to flow as a result of the different components of the blood. Blood is ...
The ventral aorta carries de-oxygenated blood from the heart to the gills; part of this vessel forms the ascending aorta in tetrapods (the remainder forms the pulmonary artery). A second, dorsal aorta carries oxygenated blood from the gills to the rest of the body and is homologous with the descending aorta of tetrapods. The two aortas are ...
The product of average velocity and ejection time gives the stroke distance (how far the blood travels in each heart cycle). Flow time (FT) is the time difference between the sudden increase in velocity (T0) and the return to near zero velocity (T1). Stroke distance (SD) can calculated from the plug flow like velocity (v(t)):
For example, hypoperfusion can be caused when an artery or arteriole that supplies blood to a volume of tissue becomes blocked by an embolus, causing either no blood or at least not enough blood to reach the tissue. Hyperperfusion can be caused by inflammation, producing hyperemia of a body part. Malperfusion, also called poor perfusion, is any ...
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The classic definition by MP Spencer and AB Denison of compliance is the change in arterial blood volume due to a given change in arterial blood pressure ().They wrote this in the "Handbook of Physiology" in 1963 in work entitled "Pulsatile Flow in the Vascular System".